U.S. patent application number 15/414997 was filed with the patent office on 2017-07-13 for magnetic multilayer structure.
The applicant listed for this patent is International Business Machines Corporation. Invention is credited to Philipp Herget, Eugene J. O'Sullivan, Lubomyr T. Romankiw, Naigang Wang, Bucknell C. Webb.
Application Number | 20170200766 15/414997 |
Document ID | / |
Family ID | 53522020 |
Filed Date | 2017-07-13 |
United States Patent
Application |
20170200766 |
Kind Code |
A1 |
Herget; Philipp ; et
al. |
July 13, 2017 |
MAGNETIC MULTILAYER STRUCTURE
Abstract
A mechanism is provided for an integrated laminated magnetic
device. A substrate and a multilayer stack structure form the
device. The multilayer stack structure includes alternating
magnetic layers and diode structures formed on the substrate. Each
magnetic layer in the multilayer stack structure is separated from
another magnetic layer in the multilayer stack structure by a diode
structure.
Inventors: |
Herget; Philipp; (San Jose,
CA) ; O'Sullivan; Eugene J.; (Nyack, NY) ;
Romankiw; Lubomyr T.; (Briarcliff Manor, NY) ; Wang;
Naigang; (Ossining, NY) ; Webb; Bucknell C.;
(Yorktown Heights, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
International Business Machines Corporation |
Armonk |
NY |
US |
|
|
Family ID: |
53522020 |
Appl. No.: |
15/414997 |
Filed: |
January 25, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15156576 |
May 17, 2016 |
9601484 |
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15414997 |
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14155552 |
Jan 15, 2014 |
9384879 |
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15156576 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 43/10 20130101;
H01F 7/021 20130101; H01L 43/12 20130101; H01F 27/24 20130101; H01L
27/22 20130101; H01F 27/2804 20130101; H01L 27/0641 20130101; H01F
1/14708 20130101; H01L 28/10 20130101; H01F 10/14 20130101; H01L
43/02 20130101; H01L 27/224 20130101; G11B 5/3163 20130101; H01F
2027/2809 20130101 |
International
Class: |
H01L 27/22 20060101
H01L027/22; H01F 27/24 20060101 H01F027/24; H01F 1/147 20060101
H01F001/147; H01L 43/10 20060101 H01L043/10; H01L 49/02 20060101
H01L049/02; H01L 43/12 20060101 H01L043/12; H01L 43/02 20060101
H01L043/02; H01F 27/28 20060101 H01F027/28; H01F 10/14 20060101
H01F010/14 |
Goverment Interests
GOVERNMENT RIGHTS
[0002] This invention was made with Government support under
Contract No. DE-EE0002892 awarded by the Department of Energy. The
Government has certain rights in this invention.
Claims
1. An integrated laminated magnetic device, comprising: a
substrate; and a multilayer stack structure which includes
alternating magnetic layers and diode structures formed on the
substrate; wherein each magnetic layer in the multilayer stack
structure is separated from another magnetic layer in the
multilayer stack structure by a diode structure.
2. The device of claim 1, wherein the multilayer stack structure
comprises repeated sandwiches of two of the magnetic layers having
the diode structure interposed in between.
3. The device of claim 1, wherein a sandwich of the magnetic layer,
the diode structure, and the another magnetic layer repeats until
the multilayer stack structure is formed of multiple
sandwiches.
4. The device of claim 1, wherein the magnetic layers are disposed
to form the multilayer stack structure by electroplating.
5. The device of claim 1, wherein the diode structures are disposed
to form the multilayer stack structure by electroplating.
6. The device of claim 1, wherein the diode structures are
forwarded bias in a same direction in the multilayer stack
structure.
7. The device of claim 6, wherein the same direction is a forward
bias direction.
8. The device of claim 7, wherein an electrical eddy current in the
multilayer stack structure is inhibited from flowing in a reverse
bias direction between the each magnetic layer and the another
magnetic layer.
9. The device of claim 6, wherein the diode structures in the
multilayer stack structure each comprise a p-type material having
positive charge carriers and an n-type material having negative
charge carriers.
10. The device of claim 1, wherein each of the alternating magnetic
layers has a thickness of about 0.3 micrometers (.mu.m) to 1.3
.mu.m.
11. The device of claim 1, wherein the alternating magnetic layers
include magnetic material.
12. The device of claim 11, wherein the magnetic material is
NiFe.
13. The device of claim 11, wherein the magnetic material is
selected from the group consisting of NiFe, CoWB, Fe, CoFeB, CoWP,
CoP, and NiFeCo.
14. The device of claim 11, wherein the magnetic material is
composition of about 80% Ni and 20% Fe to form NiFe.
15. The device of claim 14, wherein a magnetic permeability of NiFe
is 500 to 1000 H/m.
16. The device of claim 15, wherein a resistivity of NiFe is about
20 .mu..OMEGA.cm.
17. The device of claim 11, wherein the magnetic material is
composition of about 45% Ni and 55% Fe to form NiFe.
18. The device of claim 17, wherein a magnetic permeability of NiFe
is 200 to 700 H/m.
19. The device of claim 18, wherein the resistivity of NiFe is
about 40 .mu..OMEGA.cm.
20. The device of claim 11, wherein the magnetic material is CoWP;
wherein a composition CoWB is majority Co such that a magnetic
permeability I about 100 to 1000 H/m.
Description
DOMESTIC PRIORITY
[0001] This application is a divisional of and claims priority from
U.S. patent application Ser. No. 15/156,576, filed on May 17, 2016,
entitled "MAGNETIC MULTILAYER STRUCTURE" which is a divisional of
U.S. patent application Ser. No. 14/155,552, filed on Jan. 15,
2014, entitled "MAGNETIC MULTILAYER STRUCTURE", the entire contents
of which are incorporated herein by reference.
BACKGROUND
[0003] The present invention relates generally to semiconductor
integrated magnetic devices, and more specifically, to laminated
magnetic diode stack structures formed using electroplating
techniques.
[0004] When constructing a semiconductor integrated magnetic device
using a magnetic film, it is desirable to make the magnetic film
sufficiently thick to obtain desirable operating characteristics
for a given frequency of operation. However, the thickness of a
single magnetic layer that is required for a given operating
frequency of the magnetic device may result in the build-up of eddy
currents in the magnetic material during operation, thereby
resulting in some loss. As such, the magnetic film is typically
made sufficiently thin to avoid eddy current losses, but with the
tradeoff of lower energy storage ability.
[0005] The energy storage of an integrated magnetic device can be
increased, however, by building a magnetic structure using a stack
of alternating thin magnetic and insulating films, wherein the
magnetic layers are separated by a thin insulating layer. In
general, the use of multiple layers of magnetic material separated
by layers of insulating material serves to prevent the build-up of
eddy currents in the magnetic material, while providing an
effective thickness of magnetic material, which is sufficient to
obtain the desired operating characteristics for a given frequency
of operation.
[0006] Conventional techniques for building multilayer
magnetic-insulator structures include sputtering techniques. In
general, a sputtering process includes forming a multilayer stack
by alternately sputtering layers of a magnetic material and a
dielectric material, patterning a photoresist layer to form an etch
mask, using the etch mask to etch the multilayer stack of
magnetic-insulating layers and remove unwanted regions of the
multilayer stack, and then removing the etch mask. While sputtering
can be used to build stacks of magnetic-insulating layers, the
material and manufacturing costs for sputtering are high.
SUMMARY
[0007] According to an exemplary embodiment, an integrated
laminated magnetic device is provided. The device includes a
substrate and a multilayer stack structure which includes
alternating magnetic layers and diode structures formed on the
substrate. Each magnetic layer in the multilayer stack structure is
separated from another magnetic layer in the multilayer stack
structure by a diode structure.
[0008] According to another exemplary embodiment, a method for
fabricating an integrated laminated magnetic device is provided.
The method includes providing a substrate and forming a multilayer
stack structure on the substrate. The multilayer stack structure
includes alternating magnetic layers and diode structures formed on
the substrate. Each magnetic layer in the multilayer stack
structure is separated from another magnetic layer in the
multilayer stack structure by a diode structure.
[0009] According to another exemplary embodiment, a method for
fabricating an integrated laminated magnetic device is provided.
The method includes forming a seed layer on a substrate and forming
a mask structure over the seed layer in which the mask structure
exposes an exposed portion of the seed layer that defines a device
region. The method includes electroplating a first magnetic layer
on the exposed portion of the seed layer within the device region
using the seed layer as an electrical cathode or anode, forming a
diode structure on the first magnetic layer in the device region,
and electroplating a second magnetic layer on the diode structure
within the device region using the seed layer as the electrical
cathode or anode. The first magnetic layer is electrically
connected to the second magnetic layer by the diode structure being
in a forward bias direction, and a combination of the first
magnetic layer, the diode structure, and the second magnetic layer
form a sandwich.
[0010] Additional features and advantages are realized through the
techniques of the present invention. Other embodiments and aspects
of the invention are described in detail herein and are considered
a part of the claimed invention. For a better understanding of the
invention with the advantages and the features, refer to the
description and to the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The subject matter which is regarded as the invention is
particularly pointed out and distinctly claimed in the claims at
the conclusion of the specification. The forgoing and other
features, and advantages of the invention are apparent from the
following detailed description taken in conjunction with the
accompanying drawings in which:
[0012] FIGS. 1A through 1C illustrate a fabrication process for a
magnetic multilayer structure according to an embodiment, in
which:
[0013] FIG. 1A illustrates cross-sectional views of fabricating the
magnetic multilayer structure according to an embodiment.
[0014] FIG. 1B illustrates cross-sectional views of forward biasing
the magnetic multilayer structure and repeating fabrication
processes to form additional layers according to an embodiment.
[0015] FIG. 1C illustrates a cross-sectional view of the magnetic
multilayer structure according to an embodiment.
[0016] FIG. 2A illustrates an operation concept utilizing magnetic
multilayer structure with diode structures according to an
embodiment.
[0017] FIG. 2B illustrates a cross-sectional view of the magnetic
multilayer structure according to an embodiment.
[0018] FIGS. 3A, 3B, and 3C illustrate a fabrication process for a
magnetic multilayer structure according to an embodiment, in
which:
[0019] FIG. 3A illustrates cross-sectional views of fabricating the
magnetic multilayer structure with a top diode layer according to
an embodiment.
[0020] FIG. 3B illustrates cross-sectional views of forward biasing
the magnetic multilayer structure and repeating fabrication
processes to form additional layers according to an embodiment.
[0021] FIG. 3C illustrates a cross-sectional view of the magnetic
multilayer structure according to an embodiment.
[0022] FIGS. 4A, 4B, and 4C illustrate a fabrication for a
multilayer magnetic structure according to an embodiment, in
which:
[0023] FIG. 4A illustrates cross-sectional views of fabricating the
magnetic multilayer structure with a barrier layer according to an
embodiment.
[0024] FIG. 4B illustrates cross-sectional views of forward biasing
the multilayer magnetic structure and forming the top diode layer
according to an embodiment.
[0025] FIG. 4C illustrates cross-sectional views of repeating
fabrication processes to form additional layers and of the
multilayer magnetic structure according to an embodiment.
[0026] FIGS. 5A, 5B, and 5C illustrate a fabrication for a
multilayer magnetic structure according to an embodiment, in
which:
[0027] FIG. 5A illustrates cross-sectional views of fabricating the
magnetic multilayer structure according to an embodiment.
[0028] FIG. 5B illustrates cross-sectional views of forward biasing
the magnetic multilayer structure according to an embodiment.
[0029] FIG. 5C illustrate cross-sectional views of repeating
fabrication processes to form additional layers and the magnetic
multilayer structure according to an embodiment.
[0030] FIG. 6 illustrates a method for fabricating an integrated
laminated magnetic device according to an embodiment.
[0031] FIG. 7 illustrates a method for fabricating an integrated
laminated magnetic device according to an embodiment.
DETAILED DESCRIPTION
[0032] Embodiments of the invention disclose techniques to
fabricate laminate magnetic layers with diodes interposed between.
The multilayer stack of magnetic layers and diodes can be utilized
in semiconductor integrated magnetic devices such as inductors,
transformers, etc., which include laminated magnetic-diode stack
structures that are formed using electroplating techniques (and/or
in combination with other deposition techniques such as
sputtering).
[0033] With standard electroplating techniques, each magnetic layer
in a multilayer stack of magnetic-insulating layers may be as
follows. A first step involves depositing a conducting seed layer
over the entire wafer via a vacuum deposition process, e.g.,
sputtering. Optionally, an insulator may be deposited over the
wafer prior to depositing the conducting seed layer. Next, a layer
of photoresist material is deposited on the conducting seed layer,
and the photoresist material is patterned photolithographically to
form a photoresist mask that covers portions of the seed layer
where plating of magnetic material is unwanted. Subsequently, an
electrical connection is made to the seed layer (and electrolyte
solution in the tank), and an electroplating process is performed
to electroplate a layer of magnetic material (NiFe, compounds of
Ni/Fe/Co, Co--W--P, etc.) onto the portions of the seed layer that
are exposed through the photoresist mask. After the electroplating
process is performed, the photoresist mask is removed and the
residual seed layer (portions of seed layer that were covered by
the photoresist mask) is removed by reactive-ion etching (RIE) or
some other suitable etching process. Thereafter, an insulating
layer is formed over the electroplated magnetic layer.
[0034] The electroplating process is then repeated for each
additional layer of magnetic material that is deposited to form the
multilayer stack of magnetic-insulating layers. In particular,
after each insulating layer is formed, the process steps of seed
layer deposition, resist and mask alignment, resist patterning,
electroplating, resist strip, and seed layer removal are
independently performed for each layer of the magnetic stack
structure. This process repetition can be expensive and cumbersome
when the number of magnetic layers forming a stack is large.
Moreover, this process can also cause alignment problems between
the magnetic layers.
[0035] In accordance with embodiments, the electroplating process
can be simplified by eliminating the repeated steps of: depositing
and patterning a photoresist pattern, removing the photoresist
pattern, adding insulating material, and etching away the seed
layer for each layer of deposition of the magnetic material, and
performing the same steps again. In general, an electroplating
process according to embodiments involves using only one patterning
mask (that does not have to be removed for subsequent layers), and
then sequentially forming the magnetic layers and subsequent diode
structures into the multilayer magnetic stack so that each
intervening diode structure electrically isolates the magnetic
layers in the reverse bias direction while only allowing electrical
current to flow in the forward bias direction (e.g., in an upward
direction as depicted in the figures).
[0036] The diode structures are formed in between each of the
magnetic layers in the multilayer magnetic stack structure. By
forward biasing the diode structures in the same direction,
electrical current is only allowed to flow in a single direction
(e.g., forward bias direction) and eddy currents are blocked from
flowing in the reverse direction. This is because no electrical
current (i.e., eddy current) flows in the reverse bias direction
for the diode structures, each of which is individually sandwiched
between every two magnetic layers. Various techniques may be used
to construct the multilayer magnetic structures with diode
structures interposed between the magnetic layers. The various
techniques of embodiments may be combined as understood by one
skilled in the art.
[0037] Now turning to the figures, FIGS. 1A, 1B, and 1C (generally
referred to as FIG. 1) illustrate a schematic to fabricate a
magnetic multilayer structure 100 according to an embodiment. FIGS.
1A through 1C are cross-sectional views of the schematic to form
the magnetic multilayer structure 100.
[0038] FIGS. 1A through 1C (along with figures below) discuss
electroplating techniques for depositing layers. As understood by
one skilled in the art, electroplating is a process that uses
electrical current to reduce dissolved metal cations so that they
form a coherent metal coating on an electrode. The process used in
electroplating is called electrodeposition. The part to be plated
is the cathode of the circuit. In one technique, the anode is made
of the metal to be plated on the part. Both components are immersed
in a solution called an electrolyte containing one or more
dissolved metal salts as well as other ions that permit the flow of
electricity. A power supply supplies a direct current to the anode,
oxidizing the metal atoms that comprise anode and allowing the
metal atoms to dissolve in the electrolyte solution. At the
cathode, the dissolved metal ions in the electrolyte solution are
reduced at the interface between the solution and the cathode, such
that they "plate out" onto the cathode. The rate at which the anode
is dissolved is equal to the rate at which the cathode is plated,
vis-a-vis the current flowing through the circuit. In this manner,
the ions in the electrolyte bath are continuously replenished by
the anode. Other electroplating processes may use a non-consumable
anode such as platinum or carbon. In these techniques, ions of the
metal to be plated must be periodically replenished in the
electrolyte bath as they are drawn out of the solution.
[0039] Referring to FIG. 1A, a substrate 10 (such as a silicon
wafer) has a seed layer 12 deposited in preparation for
electroplating (also referred to as plating) in view 102. The seed
layer 12 may be selected to correspond to a first magnetic layer 16
(discussed below). The seed layer 12 may be deposited by any known
deposition technique as understood by one skilled in the art. For
example, the seed layer 12 may be deposited by sputtering,
evaporation or CVD.
[0040] A photoresist 14 is deposited (via any known deposition
technique) and patterned on the seed layer 12 in preparation for
electrodepositing subsequent layers during electroplating. The
resist 14 is patterned to create a device region 60 for plating the
layers in subsequent views. Various operations of the
electroplating process are discussed below.
[0041] The first magnetic layer 16 of magnetic material is
deposited on the seed layer 12 by electroplating. The thickness of
the first magnetic layer 16 may range from 0.3 micrometers (.mu.m)
to 1.3 .mu.m. Examples of the magnetic material of the first
magnetic layer 16 may include NiFe, CoWB, Fe, CoFeB, CoWP, CoP,
NiFeCo, etc.
[0042] In a case where the first magnetic layer 16 is NiFe, the
composition may be (approximately) 80% Ni and 20% Fe, the magnetic
permeability of NiFe is 500 to 1000 H/m (where H is the magnetic
field strength and m represents meter), and the resistivity of NiFe
is 20 .mu..OMEGA.cm (microOhmcentimeter).
[0043] In another case when the first magnetic layer 16 is NiFe,
the composition may be 45% Ni and 55% Fe, the magnetic permeability
of NiFe is 200 to 700 H/m, and the resistivity of NiFe is 40
.mu..OMEGA.cm.
[0044] In the case when the first magnetic layer 16 is CoWB, the
composition may be mostly Co (e.g., 75, 85, and/or 90% Co, with the
remaining material as W and P), the relative magnetic permeability
of CoWP is 100 to 1000, and the resistivity of CoWP is about 100
.mu..OMEGA.cm.
[0045] In view 104, a first diode layer 18 is deposited on the
first magnetic layer 16 in the device region 60 by electroplating.
In view 106, a second diode layer 20 is deposited on the first
diode layer 18 in the device region 60 by electroplating, thus
forming the diode structure 30. The first diode layer 18 may be a
p-type material (having more positive charge carriers) and the
second diode layer 20 may be an n-type material (having more
negative charge carriers) such that the diode structure 30 is
forward biased in the upward direction (e.g., from first diode
layer 18 to second diode layer 20) and reverse biased in the
downward direction (e.g., from second diode layer 20 to first diode
layer 18). The forward bias of the diode structure 30 (and
subsequent diode structures 30 formed in the multilayer magnetic
structure 100) only allow electrical current to flow upward thus
blocking eddy current from flowing downward as discussed
herein.
[0046] Examples (p-type) materials of the first diode layer 18 may
include Bi, Se, doped Si, doped Ge, doped (Cu,Ga) CdS or CdSe, and
CulnSe.sub.2. The thicknesses of the diode layer 18 may range from
20 nanometers (nm) to 1000 nm. Example (n-type) materials of the
second diode layer 20 may include (doped and/or updoped), Ge, Si,
CdS, and CdSe. The thicknesses of the second diode layer 20 may
range from 20 nm to 1000 .mu.m. To electroplate the first diode
layer 18, ions of the p-type material are dissolved in electrolyte
bath (solution). Voltage is applied to the seed layer 12 and to the
electrolyte bath to plate the p-type material of the first diode
layer 18. As a low cost example, the electroplating of a selenium
rectifier cell can be utilized for diode layers 18 and 20.
Selenium, as a p-type semiconductor, can form Schottky barrier or
herterojunction with n-type materials (e.g. Se/CdS). For the
electroplating of Se layer, an example electrolyte composition is
(0.1-1)[mole]H.sub.2SeO.sub.3; (10-250).times.10.sup.-3 [mole]
alkane sulfonic acid with plating current density between 0.5-5
mA/cm.sup.2 at a PH of 3-4, where mA is milliamperes and cm.sup.2
is square centimeters.
[0047] CdS thin films in turn can be deposited from a chemical bath
containing citratocadmium(II) and thiourea as described in
"Mechanism of Chemical Bath Deposition of Cadmium Sulfide Thin
Films in the Ammonia-Thiourea System In Situ Kinetic Study and
Modelization" by Ra l Ortega-Borges and Daniel Lincot, Journal of
Electrochemical Society 1993 140(12): 3464-3473, which is herein
incorporated by reference. The diode (e.g., diode structure 30,
330) as deposited has sufficient carriers but can be n-doped with
by annealing in N.sub.2 or by plating of an In layer and subsequent
annealing at 250 C. Since the required CdS layer can be as thin as
10 nm (although 50 nm is more robust), the CdS can also be vacuum
deposited as a simpler alternative.
[0048] The photoconductivity of the diode can be used to help
initiate plating of the next magnetic layer onto the diode but
becomes irrelevant once the magnetic layer is thick enough to be
opaque.
[0049] To electroplate the second diode layer 20, ions of the
p-type material are dissolved in electrolyte bath (solution).
Voltage is applied to the seed layer 12 and to the electrolyte bath
to plate the n-type material of the second diode layer 20.
[0050] In FIG. 1B, a second magnetic layer 22 is deposited on the
second diode layer 20 in the device region 60 via electroplating.
As noted above for the first magnetic layer 16, the thickness of
the second magnetic layer 22 may range from 0.3 .mu.m to 1.3 .mu.m.
Examples of the magnetic material of the second magnetic layer 22
may include NiFe, CoWP, Fe, CoFeB, etc. In a case when the second
magnetic layer 22 is NiFe, the composition may be (approximately)
80% Ni and 20% Fe, the magnetic permeability of NiFe is 500 to 1000
H/m (where H is the magnetic field strength and m represents
meter), and the resistivity of NiFe is 20 .mu..OMEGA.cm
(microOhmcentimeter). In another case when the second magnetic
layer 22 is NiFe, the composition may be 45% Ni and 55% Fe, the
magnetic permeability of NiFe is 200 to 700 H/m, and the
resistivity of NiFe is 40 .mu..OMEGA.cm. In the case when the
second magnetic layer 22 is CoWP, the composition may be mostly Co
(e.g., 75, 85, and/or 90% Co, with the remaining magnetic material
as W and P), the relative magnetic permeability of CoWP is 100 to
1000 H/m, and the resistivity of CoWP is 100 .mu..OMEGA.cm.
[0051] As seen in FIG. 1B, the diode structure 30 is in forward
bias when voltage (+V) is applied and the electrical current flows
upward through the first magnetic layer 16, through first diode
layer 18, through second diode layer 20, through second magnetic
layer 22, and into subsequent layers, but not in the reverse
direction.
[0052] View 110 illustrates electroplating additional layers to
form the magnetic stack with the desired layers all in forward
bias. FIG. 1C illustrates the multilayer magnetic structure 100
with the desired number of layers formed in the magnetic stack in
view 112. The dashed lines represent additional number of layers
deposited utilizing the fabrication operations discussed herein.
The first magnetic layer 16 and the second magnetic layer 22 may be
the same magnetic material. To electroplate the layers in FIG. 1,
the multilayer magnetic structure 100 may be moved from one tank of
electrolyte solution to another tank of different electrolyte
solution until the multilayer magnetic structure 100 is formed. For
example, there may be one tank of electrolyte solution for
depositing the first magnetic layer 16, one tank of electrolyte
solution for depositing the first diode layer 18, one tank of
electrolyte solution for depositing the second diode layer 20, and
another tank (or the same for the first magnetic layer 16) of
electrolyte solution for depositing the second magnetic layer 22.
Then, the electroplating process repeats to form additional layers
as shown in view 110. The multilayer magnetic structure 100 is
annealed to form the diode structures 30. The multilayer magnetic
structure 100 may be annealed at 220.degree. C. (Celsius).
[0053] The photoresist 14 (patterned mask), the seed layer 12, and
the substrate 10 are stripped off once the multilayer magnetic
structure 100 (including multilayer magnetic structures 300 and 400
discussed herein) is completed. When depositing the various layers,
the seed layer 12 does not have to be repeatedly deposited.
Similarly, the photoresist 14 does not have to be repeatedly
deposited, patterned, and etched in order to deposit additional
layers. In other words, a single photoresist 14 and single seed
layer 12 may be utilized throughout the fabrication operations.
[0054] FIG. 2A illustrates a schematic of an operation concept
utilizing diode structures disclosed herein according to an
embodiment. FIG. 2A is a schematic perspective view of a
semiconductor integrated magnetic device 200 having multilayer
magnetic stack structures (such as multilayer magnetic structures
100, 300, 400) according to an embodiment. The integrated magnetic
device 200 is a semiconductor integrated planar inductor device
that comprises a planar multi-turn coil structure 210 having an
input port 212 and an output port 214. The integrated magnetic
device 200 further comprises a plurality of magnetic structures 220
and 230 that surround portions of the coil structure 210 along the
"easy axis" of the integrated magnetic device 200. Each magnetic
structure 220 and 230 may be referred to as a yoke. Each magnetic
structure 220 and 230 is a multilayer magnetic structure (i.e.,
multilayer magnetic structures 100, 300, 400) comprising a
plurality of sequentially formed layers of magnetic materials and
diode materials (as discussed herein). In particular, the magnetic
structures 220 and 230 each comprise a lower stack structure that
is formed on the substrate below the coil structure 210 and an
upper stack structure that is formed above the coil structure 210.
The lower and upper stack structures of the magnetic structures 220
and 230 serve to completely enclose the portions of the coil
structure 210 along the easy axis region of the integrated device
200, thereby forming a closed loop of magnetic material that
carries the magnetic flux fields generated by current flowing
through the coil structure 210, and thereby providing a density of
magnetic material that increases the storable energy density.
[0055] Embodiments discussed below illustrate how to form the
magnetic structures 220 and 230 with diode structures 30 and 330
(diode structure 330 is introduced in FIG. 3). According to an
embodiment, FIG. 2B illustrates a cross-sectional view of the
integrated magnetic device 200 in which a breakout 250 is a
cross-sectional view of a portion of the multilayer magnetic
structure 230 (as well as multilayer magnetic structure 220). The
breakout 250 is an enlarged view to illustrate the concept of
utilizing the diode structures 30 and 330 to block eddy currents
from flowing in the reverse bias direction. Note that the diode
structures 30 and 330 are representative of the actual diode layers
disclosed herein, and the breakout 250 is not intended to
illustrate the actual diode layers (e.g., first diode layer, second
diode layer, and optionally top diode layer) of the diode
structures as these details are discussed herein. The breakout 250
shows the first magnetic layer 16 and the second magnetic layer 22
sandwiching the representative diode structure 30, 330. The dashed
lines denote additional alternating layers of the multilayer
magnetic structure 230 as discussed herein. The multilayer magnetic
structure 230 (and 330) may be any one and/or a combination of the
multilayer magnetic structures 100, 300, and 400 discussed herein
in FIGS. 1 and 3-7.
[0056] A loop 240 denotes the electrical flow of eddy currents. In
a conventional magnetic structure, the loop 240 would be closed.
That is, eddy current would flow in a complete circuit around the
loop 240.
[0057] However, in embodiments, the loop 240 is not a closed loop.
For example, the alternating electrical current in and out of input
port 212 and output port 214 of the coil structure 210 creates an
alternating magnetic field. The voltage of the alternating current
across the diode structure 30, 330 is utilized to forward bias the
diode structure 30, 330. The diode structure 30, 330 in forward
bias only allows the eddy current to flow in a single direction
(e.g., upward), and thus the eddy current cannot complete the loop
240. By having multiple sandwiches of the first magnetic layer 16,
the representative diode structure 30, 330, and the second magnetic
layer 22, the multilayer magnetic structures 230, 330 are able to
maintain the eddy current in a single upward direction. Since the
breakout 250 shows the reverse bias direction is downward, the eddy
current cannot flow down, thus breaking the complete electrical
flow of eddy current around the loop 240.
[0058] The voltage across the diode is proportional to the
cross-sectional area of the diode structure 30, 330, frequency of
the magnetic field, and peak magnetic field. The following is an
equation of the diode voltage:
Voltage V (of the diode)=2.pi.AFB (Equation 1)
[0059] In Equation 1, A is the area in square meters (m.sup.2), F
is the frequency of the magnetic field (in hertz (Hz)), and B is
the B-magnetic field strength in Tesla (T). The following is an
example to show that the diode structure 30, 330 is in forward
bias. Assume that A=1000 .mu.m2 .mu.m (width.times.height), F=1000
MHz, and B=1T. This results in a voltage across the diode of
0.6V.
[0060] Note that eddy currents are electric currents induced within
conductors by a changing magnetic field in the conductor. These
circulating eddies of current have inductance and thus induce
magnetic fields. The stronger the applied magnetic field, the
greater the electrical conductivity of the conductor, or the faster
the field changes, then the greater the eddy currents that are
developed and the greater the fields produced.
[0061] Although an example semiconductor integrated magnetic device
200 is discussed, embodiments also apply to other multilayer
magnetic structures such as transformers with laminated steel
cores.
[0062] FIGS. 3A, 3B, and 3C (generally referred to as FIG. 3)
illustrate a schematic to fabricate a magnetic multilayer structure
300 according to an embodiment. FIGS. 3A through 3C are
cross-sectional views of the schematic to form the magnetic
multilayer structure 300.
[0063] FIG. 3 incorporates fabrication processes discussed in FIG.
1, and adds an additional fabrication process for electrodepositing
the top diode layer. The fabrication processes discussed in views
102, 104, and 106 of FIG. 1 apply in FIG. 3. Referring to FIG. 3A,
the substrate 10 (such as a silicon wafer) has a seed layer 12
deposited in preparation for electroplating (also referred to as
plating) in view 102. The seed layer 12 may be selected to
correspond to a first magnetic layer 16. Also, as discussed above,
the photoresist 14 is deposited and patterned on the seed layer 12
in preparation for electrodepositing subsequent layers during
electroplating. The pattern of the resist 14 creates a device
region 60 for plating the layers in subsequent views. Various
operations of the electroplating process are discussed below.
[0064] In view 102, the first magnetic layer 16 of magnetic
material is deposited on the seed layer 12 by electroplating. The
thickness of the first magnetic layer 16 may range from 0.3
micrometers (.mu.m) to 1.3 .mu.m. Examples of the magnetic material
of the first magnetic layer 16 may include NiFe, CoWP, Fe, CoFeB,
etc.
[0065] In a case when the first magnetic layer 16 is NiFe, the
composition may be (approximately) 80% Ni and 20% Fe, the magnetic
permeability of NiFe is 500 to 1000 H/m, and the resistivity of
NiFe is 20 .mu..OMEGA.cm. In another case when the first magnetic
layer 16 is NiFe, the composition may be 45% Ni and 55% Fe, the
magnetic permeability of NiFe is 200 to 700 H/m, and the
resistivity of NiFe is 40 .mu..OMEGA.cm. In the case when the first
magnetic layer 16 is CoWP, the composition may be mostly Co (e.g.,
75, 85, and/or 90% Co, with the remaining magnetic material as W
and P), the relative magnetic permeability of CoWP is 100 to 1000
H/m, and the resistivity of CoWP is 100 .mu..OMEGA.cm.
[0066] In view 104, a first diode layer 18 is deposited on the
first magnetic layer 16 in the device region 60 by electroplating.
In view 106, a second diode layer 20 is deposited on the first
diode layer 18 in the device region 60 by electroplating, thus
forming the diode structure 30. The first diode layer 18 is a
p-type material (having more positive charge carriers) and the
second diode layer 20 is n-type material (having more negative
charge carriers) such that the diode structure 30 is forward biased
in the upward direction (e.g., from first diode layer 18 to second
diode layer 20) and reverse biased in the downward direction (e.g.,
from second diode layer 20 to first diode layer 18). The forward
bias of the diode structure 30 and subsequent diode structures 30
only allow electrical current to flow upward thus blocking eddy
current from flowing downward as discussed herein.
[0067] As discussed above in FIG. 1, examples (p-type) materials of
the first diode layer 18 may include Bi, doped Si, doped Ge, etc.,
and example (n-type) materials of the second diode layer 20 may
include (doped and/or updoped) Se, Ge, Si, etc. To electroplate the
first diode layer 18, ions of the p-type material are dissolved in
electrolyte bath (solution). Then, voltage is applied to the seed
layer 12 and to the electrolyte bath to plate the p-type material
of the first diode layer 18. To electroplate the second diode layer
20, ions of the n-type material are dissolved in electrolyte bath
(solution). Then, voltage is applied to the seed layer 12 and to
the electrolyte bath to plate the n-type material of the second
diode layer 20.
[0068] At this point, the fabrication process in view 302 differs
from FIG. 1. In view 302, a top diode layer 320 is deposited on top
of the second diode layer 20 in the device region 60 by
electroplating. Plating the top diode layer 320 is an optional
fabrication operation. The material of the top diode layer 320 may
include Cu, Ag, Au, Ni, NiFe, Co, etc. To electroplate the top
diode layer 320, an electrolyte solution (of ions) is prepared of
at least one of the materials (Cu, Ag, Au, Ni, NiFe, Co, etc.) of
the top diode layer 320. Then, voltage is applied to the seed layer
12 and the electrolyte solution for electrodeposition of the ions
of the material of the top diode layer 320 onto the second diode
layer 20. The top diode layer 320 acts a diode terminal for the
diode structure 330. As can be seen in view 302, the diode
structure 330 includes the first diode layer 18, the second diode
layer 20, and the top diode layer 320.
[0069] Referring to FIG. 3B, view 304 illustrates that the second
magnetic layer 22 is deposited on top of the top diode layer 320 in
the diode region 60 via electroplating. As noted above for the
first magnetic layer 16 (and noted in FIG. 1), the thickness of the
second magnetic layer 22 may range from 0.3 .mu.m to 1.3 .mu.m.
Examples of the magnetic material of the second magnetic layer 22
may include NiFe, CoWP, Fe, CoFeB, etc. In a case when the second
magnetic layer 22 is NiFe, the composition may be (approximately)
80% Ni and 20% Fe, the magnetic permeability of NiFe is 500 to 1000
H/m (where H is the magnetic field and m represents meter), and the
resistivity of NiFe is 20 .mu..OMEGA.cm (microOhmcentimeter). In
another case when the second magnetic layer 22 is NiFe, the
composition may be 45% Ni and 55% Fe, the magnetic permeability of
NiFe is 200 to 700 H/m, and the resistivity of NiFe is 40
.mu..OMEGA.cm. In the case when the second magnetic layer 22 is
CoWP, the composition may be mostly Co (e.g., 75, 85, and/or 90%
Co, with the remaining magnetic material as W and P), the relative
magnetic permeability of CoWP is 100 to 1000 H/m, and the
resistivity of CoWP is 100 .mu..OMEGA.cm.
[0070] As seen in FIG. 3B, the diode structure 330 is in forward
bias when voltage (+V) is applied to the seed layer 12 and the
electrical current flows upward through the first magnetic layer
16, through first diode layer 18, through second diode layer 20,
through the top diode layer 320, through second magnetic layer 22,
and into subsequent layers, but not in the reverse direction.
[0071] View 306 illustrates repeatedly electroplating additional
layers to form the magnetic stack with the desired layers all in
forward bias. FIG. 3C illustrates the multilayer magnetic structure
300 with the desired number of layers formed in the magnetic stack
in view 308. The dashed lines represent the additional number of
layers deposited utilizing the fabrication operations discussed
herein. The first magnetic layer 16 and second magnetic layer 22
may be the same magnetic material. To electroplate the layers in
FIG. 3, the multilayer magnetic structure 300 may be moved from one
tank of electrolyte solution to another tank of different
electrolyte solution until the multilayer magnetic structure 300 is
formed. For example, there may be one tank of electrolyte solution
for depositing the first magnetic layer 16, one tank of electrolyte
solution for depositing the first diode layer 18, one tank of
electrolyte solution for depositing the second diode layer 20, one
tank of electrolyte solution for depositing the top diode layer
320, and another (or the same the first magnetic layer 16) tank of
electrolyte solution for depositing the second magnetic layer 22.
Then, the electroplating process repeats to form additional layers
as shown in view 306. The multilayer magnetic structure 300 is
annealed to form the diodes structures 330. The multilayer magnetic
structure 300 may be annealed as 220 C (Celsius).
[0072] FIGS. 4A, 4B, and 4C (generally referred to a FIG. 4)
illustrate a schematic to fabricate a magnetic multilayer structure
100 with a barrier layer according to an embodiment. FIGS. 4A
through 4C are cross-sectional views of the schematic to form the
magnetic multilayer structure 400.
[0073] In FIG. 4A, view 102 is shown again from above and the
detailed discussions are not repeated again. View 102 illustrates
the substrate 10 with a seed layer 12 deposited in preparation for
electroplating, and the photoresist 14 is deposited and patterned
on the seed layer 12 in preparation for electrodepositing
subsequent layers during electroplating. Subsequent fabrication
operations of the electroplating process are discussed below. In
view 102, the first magnetic layer 16 of magnetic material is
deposited on the seed layer 12 by electroplating.
[0074] In view 402, a barrier layer 405 is deposited on the first
magnetic layer 16 in the device region 60 by electroplating. The
material of the barrier layer 405 may include NiP, CoP, and/or
other barrier materials. To electroplate the barrier layer 405, an
electrolyte solution (NiP, CoP) has ions of the materials of
barrier layer 405. The barrier layer 405 is a non-magnetic material
(i.e., NiP, CoP) with a high resistance that is thermally stable,
and still provides enough conducting to allow currents to flow
through. The barrier layer 405 interfaced between the first
magnetic layer 16 and the first diode layer 18 (subsequently
deposited) prevents the first magnetic layer 16 and first diode
layer 18 from reacting. The thickness of the barrier layer 405
(e.g., CoP and/or NiP) may range from 10 nm to 100 nm and may be
formed by a combined cell with P in the plating solution, and pulse
plating to increase the P concentration where the barrier layer 405
is desired. Also possible plated Se and a range of sputtered films
such as undoped Si and Ge may be utilized.
[0075] View 402 illustrates that a first diode layer 18 is
deposited on the barrier layer 405 in the device region 60 by
electroplating. View 402 is analogous to view 104 except the
barrier layer 405 is now added. In view 406, a second diode layer
20 is deposited on the first diode layer 18 in the device region 60
by electroplating. FIG. 4B shows that the top diode layer 320 is
deposited on top of the second diode layer 20 by electroplating in
view 408 (which is analogous to view 302 in FIG. 3A). The first
diode layer 18, the second diode layer 20, and the top diode layer
320 all form the diode structure 330.
[0076] As noted above, the first diode layer 18 may be a p-type
material (having more positive charge carriers) and the second
diode layer 20 may be an n-type material (having more negative
charge carriers) such that the diode structure 330 is forward
biased in the upward direction (e.g., from first diode layer 18 to
second diode layer 20 to the top diode layer 320) and reverse
biased in the downward direction (e.g., from second diode layer 20
to first diode layer 18). The forward bias of the diode structure
330 and subsequent diode structures 330 only allows electrical
current to flow upward thus blocking eddy current from flowing
downward as discussed herein.
[0077] View 410 illustrates that the second magnetic layer 22 is
deposited on the top diode layer 320 in the diode region 60 via
electroplating. As noted above, the thickness of the first magnetic
layer 16 and the second magnetic layer 22 may range from 0.3 .mu.m
to 1.3 .mu.m.
[0078] In view 410, the diode structure 330 is in forward bias when
voltage (+V) is applied to the seed layer 12 and the electrical
current flows upward through the first magnetic layer 16, through
barrier layer 405, through first diode layer 18, through second
diode layer 20, through second magnetic layer 22, and into/through
subsequent layers, but not in the reverse direction.
[0079] Referring to FIG. 4C, view 412 illustrates repeatedly
electroplating additional layers to form the magnetic stack with
the desired layers all in forward bias. View 414 illustrates the
multilayer magnetic structure 400 with the desired number of layers
formed in the magnetic stack. The dashed lines represent that
additional layers have been deposited utilizing the fabrication
operations discussed herein. The first magnetic layer 16 and second
magnetic layer 22 may be the same magnetic material. Examples
materials of the first magnetic layer 16, the first diode layer 18,
the second diode layer 20, the top diode layer 320, and the second
magnetic layer 22 have been discussed herein and are not
repeated.
[0080] To electroplate the layers in FIG. 4, the multilayer
magnetic structure 300 may be moved from one tank of electrolyte
solution to another tank of different electrolyte solution until
the multilayer magnetic structure 400 is formed. For example, there
may be one tank of electrolyte solution for depositing the first
magnetic layer 16, one tank of electrolyte solution for depositing
the barrier layer 405, one tank of electrolyte solution for
depositing the first diode layer 18, one tank of electrolyte
solution for depositing the second diode layer 20, one tank of
electrolyte solution for depositing the top diode layer 320, and
another (or the same the first magnetic layer 16) tank of
electrolyte solution for depositing the second magnetic layer 22.
Then, the electroplating process continuously repeats to form
additional layers as shown in view 412. The multilayer magnetic
structure 400 is annealed to form the diodes structures 330. The
multilayer magnetic structure 400 may be annealed as 220 C
(Celsius).
[0081] FIGS. 5A, 5B, and 5C (generally referred to a FIG. 5)
illustrate a schematic to fabricate the magnetic multilayer
structure 400 according to an embodiment. FIGS. 5A through 5C are
cross-sectional views of the schematic to form the magnetic
multilayer structure 400 by using other deposition techniques,
e.g., other than and/or in addition to electroplating, for some
diode layers in the magnetic multilayer structure 400.
[0082] FIG. 5A illustrates the fabrication processes in views 102
and 104 previously discussed herein. As noted above, the seed layer
12 is deposited on the substrate 10 and the photoresist 14 is
deposited and patterned on the seed layer 12 in preparation for
depositing subsequent layers. The first magnetic layer 16 of
magnetic material is deposited on the seed layer 12 by
electroplating. In view 104, a first diode layer 18 is deposited on
the first magnetic layer 16 in the device region 60 by
electroplating. The first diode layer 18 may also be deposited by
other deposition techniques such as sputtering, and the material of
the first diode layer 18 may include Al, Ta, and Ga (when
sputtered).
[0083] View 502 illustrates sputtering the second diode layer 20 on
top of both the first diode layer 18 and the photoresist 14. The
second diode layer 20 may be a semiconductor material. The material
of the second diode layer 20 may include Si, Ge, Se, etc.
[0084] View 504 illustrates that the top diode layer 320 is
deposited on top of the second diode layer 20 in the device region
60 by electroplating. The top diode layer 320 may also be deposited
utilizing other deposition techniques. In FIG. 5B, view 506
illustrates that a wet etchant has been utilized to etch off the
excess semiconductor material of the sputtered second diode layer
20. The excess semiconductor material of the sputtered second diode
layer 20 was located on the resist 14. The first diode layer 18,
the second diode layer 20, and the top diode layer 320 all form the
diode structure 330.
[0085] FIG. 5B also shows the view 304 which illustrates that the
second magnetic layer 22 is deposited on top of the top diode layer
320 in the diode region 60 via electroplating. As noted above, the
first magnetic layer 16 and the second magnetic layer 22 may each
have a thickness in the range from 0.3 .mu.m to 1.3 .mu.m. The
diode structure 330 is in forward bias when voltage (+V) is applied
to the seed layer 12 and the electrical current flows upward
through the first magnetic layer 16, through first diode layer 18,
through second diode layer 20, through second magnetic layer 22,
and into subsequent layers, but not in the reverse direction (as
discussed in FIG. 3B).
[0086] FIG. 5C also includes views 306 and 308 discussed above in
FIG. 3.
[0087] View 306 illustrates repeatedly depositing additional layers
to form the magnetic stack with the desired layers all in forward
bias. FIG. 5C illustrates the multilayer magnetic structure 300
with the desired number of layers formed in the magnetic stack in
view 308. Again, the dashed lines denote that additional layers
have been deposited utilizing the fabrication operations discussed
herein. The first magnetic layer 16 and second magnetic layer 22
may be the same magnetic material. The multilayer magnetic
structure 300 may be annealed at 220.degree. C. to form the diodes
structures 30.
[0088] FIG. 6 illustrates a method 600 for fabricating an
integrated laminated magnetic device (i.e., multilayer magnetic
structures 100, 300, 400) according to an embodiment.
[0089] The substrate 10 is provided at block 605. A multilayer
stack structure is formed on the substrate 10, in which the
multilayer stack structure includes magnetic layers 16, 22 and
diode structures 30, 330 formed on the substrate 10 at block
610.
[0090] At block 615, each magnetic layer 16 in the multilayer stack
structure is separated from another magnetic layer 22 in the
multilayer stack structure by a diode structure 30, 330.
[0091] The multilayer stack structure comprises repeated sandwiches
of two of the magnetic layers 16 and 22 having the diode structure
30, 330 interposed in between. The sandwich of the magnetic layer
16, the diode structure 30, 330, and the other magnetic layer 22
repeats until the multilayer stack structure is formed of multiple
sandwiches (shown as multilayer magnetic structures 100, 300,
400).
[0092] The magnetic layers are disposed to form the multilayer
stack structure by electroplating. The (first diode layers 18,
second diode layer 20, top diode layers 320 of the) diode
structures 30, 330 are disposed to form the multilayer stack
structure by electroplating.
[0093] The diode structures 30, 330 are forwarded bias in a same
direction in the multilayer stack structure, such that the same
direction is a forward bias direction. An electrical eddy current
in the multilayer stack structure is inhibited from flowing in a
reverse bias direction between the each magnetic layer and the
other magnetic layer (as shown in FIG. 2).
[0094] The diode structures 30, 330 in the multilayer structure
each comprise a p-type material having positive charge carriers and
an n-type material having negative charge carriers.
[0095] FIG. 7 illustrates a method 700 for fabricating an
integrated laminated magnetic device (i.e., multilayer magnetic
structures 100, 300, 400) according to an embodiment.
[0096] A seed layer 12 is formed on a substrate 10 at block 705. A
mask structure (e.g., patterned photoresist 14) is formed over the
seed layer 12, in which the mask structure exposes an exposed
portion of the seed layer 12 that defines a device region 60 at
block 710. Electroplating deposits a first magnetic layer 16 on the
exposed portion of the seed layer 12 within the device region 60
using the seed layer 12 as an electrical cathode or anode (e.g.,
the seed layer 12 is connected to the negative or positive terminal
of the voltage source) at block 715.
[0097] A diode structure 30, 330 (e.g., of the first diode layer
18, the second diode layer 20, and optionally the top diode layer
320) is formed on the first magnetic layer 16 in the device region
60 at block 720. Optionally, the barrier layer 405 may be deposited
on the first magnetic layer 16 before the depositing the diode
structure 30, 330. Electroplating deposits a second magnetic layer
22 on the diode structure 30, 330 within the device region 60 using
the seed layer 12 as the electrical cathode or anode at block
725.
[0098] The first magnetic layer 16 is electrically connected to the
second magnetic layer 22 by the diode structure 30, 330 being in a
forward bias direction at block 730. The combination of the first
magnetic layer, the diode structure, and the second magnetic layer
form a sandwich.
[0099] A multilayer stack structure is constructed of multiple
sandwiches having multiple first magnetic layers 16, multiple
second magnetic layers 22, and multiple diode structures 30, 330.
One of the multiple diode structures is interposed between one of
the multiple first magnetic layers 16 and one of the multiple
second magnetic layers 22.
[0100] The multiple diode structures are forwarded bias in a same
direction in the multilayer stack structure, such that an
electrical eddy current in the multilayer stack structure is
inhibited from flowing in a reverse bias direction between each of
the multiple first magnetic layers and the multiple second magnetic
layers.
[0101] For illustration purposes, various deposition techniques are
discussed below and can be utilized in embodiments, as understood
by one of ordinary skill in the art. Thin film deposition is the
act of applying a thin film to a surface which is any technique for
depositing a thin film of material onto a substrate or onto
previously deposited layers. Thin is a relative term, but most
deposition techniques control layer thickness within a few tens of
nanometers. Molecular beam epitaxy allows a single layer of atoms
to be deposited at a time. Deposition techniques fall into two
broad categories, depending on whether the process is primarily
chemical or physical. Chemical vapor deposition utilizes a fluid
precursor that undergoes a chemical change at a solid surface,
leaving a solid layer. Chemical deposition is further categorized
by the phase of the precursor and examples of chemical deposition
include, but are not limited to: plating; chemical solution
deposition (CSD) or chemical bath deposition (CBD); spin coating or
spin casting; chemical vapor deposition (CVD); plasma enhanced CVD
(PECVD); atomic layer deposition (ALD); and so forth.
[0102] Physical vapor deposition (PVD) uses mechanical,
electromechanical, or thermodynamic means to produce a thin film of
solid. Examples of physical deposition include but are not limited
to: a thermal evaporator (i.e., molecular beam epitaxy); an
electron beam evaporator; sputtering; pulsed laser deposition;
cathodic arc physical vapor deposition (arc-PVD);
electrohydrodynamic deposition (electrospray deposition); reactive
PVD; and so forth.
[0103] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one or more other features, integers,
steps, operations, element components, and/or groups thereof.
[0104] The corresponding structures, materials, acts, and
equivalents of all means or step plus function elements in the
claims below are intended to include any structure, material, or
act for performing the function in combination with other claimed
elements as specifically claimed. The description of the present
invention has been presented for purposes of illustration and
description, but is not intended to be exhaustive or limited to the
invention in the form disclosed. Many modifications and variations
will be apparent to those of ordinary skill in the art without
departing from the scope and spirit of the invention. The
embodiment was chosen and described in order to best explain the
principles of the invention and the practical application, and to
enable others of ordinary skill in the art to understand the
invention for various embodiments with various modifications as are
suited to the particular use contemplated.
[0105] The diagrams depicted herein are just one example. There may
be many variations to this diagram or the steps (or operations)
described therein without departing from the spirit of the
invention. For instance, the steps may be performed in a differing
order or steps may be added, deleted or modified. All of these
variations are considered a part of the claimed invention.
[0106] While the preferred embodiment to the invention had been
described, it will be understood that those skilled in the art,
both now and in the future, may make various improvements and
enhancements which fall within the scope of the claims which
follow. These claims should be construed to maintain the proper
protection for the invention first described.
* * * * *